I presume this is in stores as well. Doesn't come with Kinect though.
50 bucks for a 250GB hard drive on eBay:
http://www.ebay.com.au/itm/Black-250GB-Hard-Drive-Disk-HDD-X…
Edit: In stores as well if you don't want to wait:
http://www.jbhifi.com.au/games/microsoft/x-box/360/
I was just gonna post that. After see this
http://www.ozbargain.com.au/node/55830